The term "mass shootings" brings to mind infamous episodes of mass murder in schools - Columbine, Sandy Hook, Marjory Stoneman Douglas, Santa Fe - at military bases - Fort Hood, Washington Yard and at entertainment and leisure venues - the Pulse nightclub, a music festival in Las Vegas, a movie theater in Colorado, a Waffle House restaurant in Tennessee.

Such shootings garner wall-to-wall coverage and extensive speculation about the often-unknowable "why." These incidents occur in the public eye, and the 24-hour news cycle magnifies the horror and keeps each incident squarely in the public discourse, at least for a few days.

But a mass shooting is not defined by its location. According to the FBI, a mass shooting is, quite simply, the murder, by gun, of four or more people. Note that if the shooter kills himself, that is not considered part of the body count. After the Newtown, Connecticut, school shooting, Congress passed P.L. 112-265, defining a mass killing as one where three or more people died.

The Department of Homeland Security found that in 2017, there were 28 incidents of "mass attacks," which it defined as an occurrence in a public space where three or more people were harmed. It is a sad and sobering reflection on our society that we are having this conversation at all, let alone searching for the most precise definition.

With the FBI criterion in mind, the organization Everytown for Gun Safety pored over seven years of FBI data on mass shootings. It found that a staggering 54 percent of mass shootings that occur in the United States are related to domestic or family violence, and most occur in a private setting, like the home.

The organization also found that in 42 percent of these killings, the perpetrator had exhibited warning signs, including known violent behavior toward an intimate partner, children and other relatives. In some cases, the perpetrator's actions had been reported to the police.

These mass shootings are covered in the local media but rarely make the national news. They are not spectacular enough; they are merely grim statistics. Yet the perpetrators of public and private mass shootings have more in common than just the guns they use - often, they have links to domestic violence.

Some of the most notorious incidents were perpetrated by people with a history of domestic violence, whose rage eventually spilled out onto the public. Devin Kelley, who killed 26 people in a Sutherland, Texas, church, in November 2017, had a history of domestic abuse and harassment, including choking his first wife and fracturing the skull of his young stepson. He remarried, and started texting threats to his mother-in-law. Kelley targeted the church because he expected her to be at the service.

Nikolas Cruz killed 17 people at Marjory Stoneman Douglas High School in Parkland, Florida, in February 2018. Cruz was the subject of dozens of calls to law enforcement, including one incident where he slammed his mother into a wall for taking away his Xbox.

In May 2018, 17-year-old Dimitrios Pagourtzis entered Santa Fe High School in Santa Fe, Texas, and shot 23 people, 10 of whom died. One of the victims was a girl who had refused his advances, and he became increasingly aggressive over the months he pursued her.

Stephen Paddock, who murdered 56 and injured more than 550 concertgoers in Las Vegas in October 2017, was known at the casinos he frequented for his high-stakes gambling - and for verbally abusing his girlfriend.

Omar Mateen regularly beat his first wife and she divorced him after four months of marriage, saying that her family literally had to pull her from his arms. On June 12, 2016, Mateen murdered 49 people at the Pulse nightclub in Orlando.

On the same day as Mateen's shooting spree, Juan David Villegas-Hernandez murdered his wife and four children in Roswell, New Mexico. She had asked for a divorce, citing domestic abuse.

Mateen is still a household name, but most of us are unaware of Villegas-Hernandez's crime, his flight to Mexico, his capture and eventual extradition back to the United States. Villegas-Hernandez was local news, yet he and others like him are responsible for the bulk of mass shootings. Perhaps they should be our focus.

The victims may be targeted, and the shootings rarely occur in public venues, but when they do, bystanders are at risk.

In June 2016, Jason Dej-Odoum followed his wife to a Walgreens, shot her in the parking lot, then drove to their home in Las Vegas and killed their three children before turning the gun on himself. His wife had applied for an order of protection but her application was denied.

On April 10, 2017, Cedric Anderson entered an elementary school in San Bernardino, California, walked into his estranged wife's special education classroom and shot her. Anderson also killed one of her students and injured another before killing himself.

Children who observe incidents of domestic violence can be profoundly affected. Fear and anxiety for themselves, siblings or a parent are major stressors. Exposure to domestic violence can make children feel isolated and vulnerable. Many withdraw and experience difficulties in school and social situations, problems which will cause more withdrawal. And children exposed to violent behavior may learn to engage in it themselves.

On January 23, 2018,15-year-old Gabriel Parker brought his stepfather's gun to his high school in Benton, KY. He killed two classmates and injured 14 others. Parker had apparently been planning the attack for more than six months, posting hints on Snapchat. Parker's parents divorced when he was five. His father served 90 days in jail on a disorderly conduct charge related to a domestic violence incident. In her petition for a domestic abuse order, Austin Parker's then-wife called him controlling and a bully.

In the fall of 2016, 14-year-old Jesse Osborne took his father's gun and murdered him. After kissing his pet rabbit and dogs good-by, Jesse drove his father's pickup truck to a Townville, South Carolina, elementary school, where he killed a 6-year-old boy and injured four others, including a teacher. In an interview with the FBI and a sheriff's county investigator, Osborne claimed his father was often drunk and "fussing at" him and his mother and "in my face." Osborne had been in trouble and had been suspended after bringing a machete and a hatchet to school. At the time of the shooting, he was being home schooled and was part of an online group that discussed and planned school shootings.

While numerous factors intertwine to lead an individual from hitting a spouse to shooting up a public venue, or from acting out at home to shooting up a school, the often lethal combination of domestic violence and easy access to guns should not be ignored.

The Parkland shooting led to groundswell of political activity to tighten the gun laws in this country. Proponents often point to Australia as a model of sensible gun laws, which were put into place after a mass shooting in 1996. Australia has a 28-day waiting period, requires a justifiable reason to own a gun, and conducts rigorous background checks. The government also bought back and destroyed one million semi-automatic weapons - about a third of Australia's firearms. There has not been another mass shooting since the 1996 incident, and murder and suicide rates have dropped dramatically.

But the Australian approach is unlikely to work in the United States, if for no other reasons than the reverence many feel for the Second Amendment and the sheer numbers of weapons in our country. As of 2009, the last year for which Department of Justice data is available, the United States had 101 guns per 100 people.

Beefed-up federal laws are a worthy goal, including stronger background checks, and closing gun show and private sale loopholes. But in the absence of federal action, states are leading the way. Seven governors, New York's among them, recently announced the formation of "States for Gun Safety," a multistate consortium to study gun violence and public health.

Twenty-seven states prohibit a person subject to a domestic violence restraining order or convicted of a domestic violence offense from possessing firearms. This has only a limited effect on intimate partner homicide rates, because those subject to a restraining order are not required to relinquish the guns they already own. States that require relinquishment - either after conviction (11 states) or for the period a person is under a restraining order (15 states) - have seen significant reduction in domestically related gun homicides. Even so, relinquishment laws are difficult to enforce so are not as effective as they could be.

Six states have what are called "red flag" laws. In California, for example, a concerned acquaintance or family member can ask a court to allow police to temporarily seize the guns of someone at imminent risk of harming him or herself or others. In some other states, the police must petition the court. It is difficult to measure the effectiveness of a law that keeps something from happening - i.e., a homicide - but about a dozen states are looking into the ramifications of implementing such a law. Other states are looking at secure storage laws and requiring background checks for some private sales.

On May 1, 2018, New York joined the states requiring relinquishment when the Governor signed legislation expanding the list of "serious" crimes which, upon conviction, require the loss of a gun license and the surrender of all firearms. The intent of this legislation is "to ensure no domestic abuser in New York retains the ability to possess a firearm once convicted of a disturbing crime."

One thing we know from the U.S. Supreme Court decision in District of Columbia v. Heller: "[T]he right secured by the Second Amendment is not unlimited" and does not invalidate "prohibitions on the possession of firearms by felons and the mentally ill, or laws forbidding the carrying of firearms in sensitive places such as schools and government buildings, or laws imposing conditions and qualifications on the commercial sale of arms."

Even modest limitations have good public health and safety outcomes. A number of New Yorkers are still calling for repeal of New York's Safe Act, which in 2013 implemented certain firearm restrictions. But since its passage, the number of violent crimes committed with a firearm decreased from 12,235 to 10,007 in 2016. And New York has one of the lowest suicide rates in the country.

Student survivors of the mass shooting earlier this year at Marjory Stoneman Douglas High School launched the #NeverAgain movement, which has inspired hundreds of thousands of Americans to participate in protests and call for stricter gun laws. Will political activism in the streets lead to stricter, smarter guns laws and a reduction in mass shootings and all gun-related violence? Will Americans take a closer look at the risk factors that can lead individuals to engage in gun violence? That remains to be seen.

Selected Sources

Annals of Internal Medicine, Oct. 2017, study funded by the Robert Wood Johnson Foundation, used by Prevent DV Gun Violence.org.

Mass Shootings in the United States: 2009-2016 and Appendix. Everytown for Our Safety, 2017.

What Works to Reduce Gun Deaths, The Economist, Mar. 22, 2018.

Understanding the Second Amendment, Report of the NYSBA Task Force on Gun Violence, 2015.

Mass Murder With Firearms: Incidents and Victims, 1999-2013, Congressional Research Service, 2015.

Mass Attacks in Public Spaces, National Threat Assessment Center, U.S. Secret Service, Dep't of Homeland Security, Mar. 2018.

Press Release: Governor Cuomo Signs Legislation to Remove Guns From Domestic Abusers, Office of the Governor, May 1, 2018.

District of Columbia v. Heller,  554 U.S. 570, 626-27 (2008).